Johnson's concerns are not unreasonable, says Tessa Hill, cofounder of Minneapolis-based advocacy group Kids for Saving Earth. Hill, who also serves on the advisory board for the U.S. Environmental Protection Agency's children's health office, points out that most of the standards governing air quality were set more than 20 years ago. More recent regulations regarding pesticides on foods, she adds, specify that "everything that is tested by the EPA in terms of safety has to be ten times safer for kids. The same should go for air quality. It should be ten times safer for kids."

School administrators may not be ready to go that far. But they do realize, says Haydon, that the concern about air quality is here to stay--and not just because of the occasional cough and sniffle. As education officials fret over student test scores, they are beginning to worry about what kids are breathing while they wield a No. 2 pencil. "That's basically the reason we're spending lots of money on this," Haydon says. "We believe that the air quality does have an influence on student achievement. We said, 'Hey, if there's high CO2 readings, you tend to get sleepy, lose concentration.'"

"As a kid I would fall asleep in school a lot," echoes Audrey Johnson. "It was like passing out. But when I think back, I realize that it mostly happened in certain rooms--the ones with no windows, where it was very hot and the doors were closed. We're starting to realize that that was not just from staying up late."